Fuel pump for reversible combustion engines



Aug. 9, 1938. H. WALT] FUEL PUMP FOR REVERSIBLE COMBUSTION ENGINES Filed June 18, 1935 2 Sheets-Sheet 1 ANGLES UFADV/l/VC A. 9, 1938. H. WALTI FUEL PUMP FOR REVERSIBLE COMBUSTION ENGINES Filed June 18, 1935 2 Sheets-Sheet 2 Patented Aug. 9, 1938 a: 1

meets PATENT O FEiQE FUEL P MP on REVERSIBLE COMBUSTION ENGINES Heinrichl Walti, Winterthur-Wulflingen, Switzerland, assignor to SulzerFreres, Societe. Anonyme, Winterthur, Switzerland Application June 18,

1935, Serial No. 27,247

In Switzerland June '20, 1934 p j 8 claims.

This'invention'relatesto' a fuel pump for reversiblecombustion engines. I

One object of the invention is to avoid the necessity of shifting the pumptiming or the timing of the pump drive in reversible combustion'engines. In the form shownjit is characterized by the fact thatthe pump piston is driven by a cam having one face for use in one direction of rotation and another face for use in the other direction of rotation, without any shifting of the cam when the engine is reversed. At the same time not only the beginning but also the end of the delivery period may be changed when the engine operates under light load.

One advantage of the invention is that on account of the use of, the above described cam it is unnecessary to adjust the fuel pump in combustion engines evenfor a considerable difference in engine speed, for example, from full load to idling. The great difference of the number of revolutions under full load as compared with idling makes itnecessary that the delay of thebeginning of the fuel injection as compared to the beginning of the fuel delivery by the fuel pump required for full load at low revolutions, be reduced for smaller loads,in order to prevent uneven operation and possibly misfiring of the engine under such loads. v

The drawings illustrate one form of the invention more or lessdiagrammatically.

Figure 1 is a diagram showing the, change in the beginning of the fuel delivery and the change in the end of the fuel delivery.

Figure 2 is a diagram showing the shifting'of beginning and end of the fuel delivery in the crank diagram;

Figure 3 is a cross section through the fuel p mp; f

Figure 4 illustrates diagrammatically the position of an eccentric shaft for one position of the regulator;

Figure 5 is a similar View showing the same shaftin a different position;

Figure 6 illustrates a secondeccentric shaft in one position of adjustment;

Figure 7 is a similar view showing the second shaft in a different position of adjustment;

Figures 8 and 9 illustrate a modified arrangement of valves.

Like parts are designated by like characters throughout the specification and drawings.

it The diagram of Figure 1 illustrates the effect of the operation above described in connection generally with the engine and in connection specifically with Figures 4 to 7 inclusive. In Figure 1,

the ordinates of the linea indicate the corresponding angle of the beginning of fuel injection ahead of upper dead. center and the ordinates of line b indicate the angle of the end of fuel delivery ahead ofupper dead center. When the power is reduced," that is to say, when the delivery of fuel .is to be reducedythe regulating means whether automatic or manual, first changes only the angle of delivery of fuel toward "upper dead center. Thus at the beginning of drop from greatest power. the angle of beginning of fuel delivery only is shifted. When however, power is dropped to the position L1 of Figure 1, then and as the power drop continues thereafter, the angle of the end of delivery moves from upper dead center as the angle of the beginning of delivery also moves so that at idling, the endof fuel delivery occurs wellbefore the pump piston reaches upper dead center.

Figure 2 shows diagrammatically the angles just mentioned in' positions of crank rotation. When the engine develops its greatest power, fuel delivery begins at A and is carried to B which corresponds with upper ,dead center. When the power developed is that indicated at L1 on Figure 1, fuel delivery begins at A1, but the end of de livery is still at B. From that point further the fuelquantity is reduced by a further shifting of the point A as well as the point B so that when the engine is idling, fuel is delivered only between pointsAzandBi. 7

There is shown in Figure 3, one form of a fuel pump of acombustion engine. The engine it self is not shown. Reference character I, designates generally the pump. 2 is a cam shaft which is connected to the engine crank shaft. It carries a cam 3, having a cam face,4, and a second cam face 5. The cam in its rotation contacts a roller ,6 which is journaled in the free end of a rocker arm or lever I. This lever carries a curved nose or bearing portion 1a, by means of which the pump piston 8, is reciprocated in response to movement of the lever which is caused by rotation of the cam. The pump piston 8 at its lower end contacts a generally cylindrical guide bushing I B. A spring "I I, beingpositioned atone end within the guide bushing I0 and at its other end upon a portion of the pump housing, surrounds the pump piston, lies partly within the bushing III and tends to push the piston downwardly. As shown, the piston is provided with alaterally extending flange Be at its lower end, upon which a cup-shaped member 8b is positioned. The lower end of the spring bears against the cup-shaped member 81). i

12 is the suction or intake fuel line through which fuel enters the pump housing. 13 is a suction valve positioned to control a passage or conduit l4, within the pump housing and communicating with the pump chamber I5. Communicating with the pump chamber I5, is a pressure or discharge valve l6, which controls the movement of fluid from the pump chamber to the pressure line l1. I8 is a passage connecting the pump chamber I5 with a return valve 20 positioned to control the passage of fuel through the port 21 back to the suction line I2.

The passage of fuel through the pump is thus from the suction line [2, past the valve l3, through the passage l4, to the pump chamber l5. When pressure in the chamber is suflicient to unseat the valve l6, fuel passes the valve and is discharged into the pressure line I1, and will be delivered to any suitable point, for example, an injection valve. When the relief or return valve 20, is open, pressure cannot rise to a sufficient point to unseat the valve 16, and hence during the time that the valve 20 is open, fuel moves through the passage l'8 past the valve 20. through the port 2 I, and back to the suction line l2.

The means for controlling the movement of the valves just mentioned and hence the means for controlling themovement of fuel, will now be described. 22 is a lever which is connected by means of an adjustable link 23, with a pin 24, on the lever 1. The lever 22 is mounted upon an adjustable eccentric shaft 25. The lever 22 adjacent its upper end carries a projection or shoulder 26, upon which the lower end of the valve stem 21, rests. A spring 28, positionedabout the valve stem 21, presses it downwardly. When the valve stem 21 is sufficiently raised by the movement of the lever 22, and the consequent movement of the shoulder 26, the suction valve I3, is raised from its seat. The movementof the valve stem 21 and its raising and lowering of the valve I3, depends upon the position of adjustment of the shaft 25 which will be-described below. 29 is a lever 3 I, which lever is journaled on an adjustably positioned eccentric shaft 32. Adjacent its upper end, the lever 3| is provided with a shoulder or projection 35. The lower endof a composite valve stem 33, 34 rests upon the shoulder 35, and is held downward upon it by a spring 40. As mentioned above, the valve stem 33, 34, is a composite or built-up unit and it is formed of a lower portion 33, into which the upper portion 34, is screwed. By means of this construction, the length of the stem may be varied to adjust the amount of play 36, between the :upper end of the valve stem portion '34, and the return or relief valve 20. r

The eccentric shaft 25, has fixed upon it an adjusting means comprising a gear section 31, which meshes with a corresponding gear sector 38 on the eccentric shaft 32. A rod 39 may be moved'backward or forward to effect adjustment of the eccentric shafts just mentioned andsince the gear sectors on the shafts mesh with each other, the movement of the shafts in response to movement of the member 39 will be-equal and opposite.

As above indicated the cam 3 drives the 'pump' for forwardmovemen't as wellas for reverse and to accomplish a change in direction, the cam need not be shifted nor need the roller 6 be raised. As shown in Figure 3, the pump piston is at lower dead center, when the cam 3 continues its rotation in the direction of the arrow, the roller 6 runs along the face 4 and commences the inward or compression stroke of the piston. After the point or nose of the cam has passed beyond the roller, the roller runs down the face 5. The pump piston is forced outwardly and accomplishes a suction stroke.

When direction of rotation of the engine is reversed, the function of the cam faces 4 and 5 is reversed and thus face 5 raises the roller to accomplish a compression stroke of the pump plunger and face 4 lowers it to accomplish a suction stroke. The cam shaft is, of course, driven from the engine, preferably from the engine crank shaft by means of gears, chain transmission or by any other desirable means. The parts are so related and timed that when the corresponding engine piston has reached upperdead center, the roller 6 has reached its highest position, between the cam faces 4 and 5, and the pumpplunger is therefore in upper dead center.

As shown in Figure 3, the suction valve I3 is closed and thestem 21 is resting upon the shoulder 26. When the movement of the cam continues in the direction of the arrow, the roller 6 is raised upon the cam face 4, and the lever 22 is rotated counterclockwise, thus lowering the shoulder 26. As shown in Figure 4, in full lines, the parts occupy the same position shown in Figure 3. The dotted line position -is that which the parts assume when the roller 6 has been raised along the cam face 4 to its uppermost point. 4| is the center line of the lever 22 in the diagram of Figures 4 and 5. When the piston makes its inner stroke, the center line moves from position a to position b and the shoulder 26-drops from position to position at. The center line of the eccentric .25 thus has position I for the greatest load. It will be seen thus that valve I3 is closed at lower dead center of the piston 8 and the piston thus for this position'of adjustment of the eccentric 25 delivers fuel during its-entire inward stroke. Thus the maximum amount of fuel is injected and the engine develops maximum power. .During the upward stroke of the piston, the valve I3 cannot fall even though the shoulder 26 is lowered because the valve is closed at the outset and thestem 21 drops away from the valve but does not open it.

When :the eccentric shaft 25 is moved from position I of Figures 3 and 4, to position 11 of Figure 5, the fulcrum of the lever 22 is thus raised. In this position with the center line 4| at position a, valve I3 is raised from its seat. The valve and lever parts in Figure assume the position shown when the pump piston is at lower dead center as shown in Figure 3. When the cam continues its movement,-the roller 6 is raised moving along the cam face 4 and the center line of lever 22 is moved to position b. The shoulder 26 is lowered from position 0 to position d. This movement of the shoulder lowers the stem 21 and lowers the valve l3, which however does not close fully until the shoulder 26 has reached position (1. This position with the center line of the lever 22 in position b corresponds to the uppermost position of the roller 6, or inner dead center of the pump piston 8. Thus when the eccentric '25 has been moved to position II as shown in Figure 5, fuel returns through the open valve l3 during the entireinward or compression stroke of the pump piston which thus. delivers no fuel. When the eccentric 25 is many position between position I of Figure 4 and position II of Figure 5, the valve I3 is open for a greater or less time during the firstportion of, the inward or compressionstroke of the pump piston. It remains open until the shoulder 26 by reason of'the rotation of the lever 22 has dropped sufficiently to permit the valve E3 to seat .and to cut off return flow of fuel from the "pump chamber. When that occurs, fuel delivery from the pump commences.

.The operation ofsthe return or relief valve 29 will now be described. When thelever 22 is moved counterclockwise by the raising of the cam roller 6 in response to rotation of the cam 3 and the shoulder 2619f lever 22 falls as the roller 6 is raised, the shoulder 35 ofthe lever 3l which engages. the blockii l :is rotated in a clockwise direction andtherefore oppositely to the layer 22. However, because a certain amount of pla 36 is provided between the stem 3t and the valve 20, when the parts are in the adjustment shown I in Figures 3 and 6, the valve 20 is not raised even at inner dead center of the pump piston, hence return flow of fuel does not occur past the valve v20 and fuel delivery takes placeduring the entire compression stroke of the pump piston. Thus when the eccentric 32 is at position III as shown in Figure 6, the delivery of fuel is not interrupted and continues to upper dead center of the pump piston 8. With the eccentric 32 in the position shown in Figures 3 and 6, the center line 42 is in the. position e of Figure 6 which corresponds to the position of outer dead center of the pump piston and the movement from outer deadcenter to inner dead center is the movement fromposition (2 to position 1, of Figure 6 audit is not sufficient to raise thevalve stem 33, 34 to contact the valve 20. U

When the eccentric 32 is rotated to position IV the fulcrum of the lever ,34 is of course raised and the center line 42 of the lever 3i occupies position e of Figure 7, and the play 36 between the stem 33, 34, and thereturn valve 20 has disappeared. When the pump piston is at outer dead center with the parts in the adjustment of'Figure '7, the center line of lever 3| is at position e. When the pump piston is moved to inner dead center, the center line moves. to position f of Figure 7. During this movement from position 6 to position 1, the shoulder 35 moves fromposition g to position h, whichisnot sufiicient to cause any raising of, the valve '26. The position IV of the eccentric 32 as shown in Figure 7 corresponds to the ordinate L1 of Figure 1. @When,

1 however, theeccentric 32 is further rotatedv to any point between positions IV and Vof Figure '7, the return valve 2i! will be raised sometime before inner dead center of the pump-piston 8. As soonas this occurs, pressure in the pump chamber l drops because dischargeof fuel past the valve 20 occurs and fuel delivery to the pressure line I? l is stopped and during the remainder of. the inward stroke of the piston, fuel in the chamber i5 is returned through the valve 20, the port 2| into the suctionline I2.

One advantage of the present invention is that the injection of fuel into the engine cylinder begins near upper dead center independent of the compression of fuel in the fuel pressure line. In slow running engines, particularly the symmetrical cam 4, because of its early beginning of fuel delivery requires preferably insertion ofa delay space in the pressure line which may be either in the form of a larger chamber in the line or in the form of an increased length of line. such a construction, the reduction of the fuel quantity for small loads were produced only by the closing of the suction or intake valve, then the beginning of fuel delivery from the pump to the engine would approach so closely upper dead center of the pump position and consequently the upper dead center of the engine piston that injection would in reality not take place at or before upper dead center but only sometime after upper dead center when the highest compression pressures and the highest compression temperatures in the engine have been passed and thus fuel ignition would become doubtful. This danger is avoided by the construction of the present invention.

It will be realized that while I have shown and described an operative device, nevertheless many changes may be made in the size, shape, number and disposition of parts without departing materially from the spirit of my invention.- I wish, therefore, that my showing and, description shall be taken in a broad sense as diagrammatic. Particularly the forms of the valve shown both for intake and relief might be widely varied and while generally conical valves have been shown, the invention is not limited to this type of valve nor to any particular type of valve, and in fact the return passages in the pump cylinder mightbe controlled by the pump piston itself. The return might also be made by valves of any type located in the suction and return passages.

In-Figures 8 and 9, the valves are located on the same side of the pump piston and they are mounted upon the same eccentric shaft. In general, however, the operation of the device in this form of the invention is essentially that of the device above described and since the parts are the same except for the re-arrangement, they need not be described again in detail.

Iclaim:

1. In combination in a fuel pump for internal combustion engines, a pump cylinder and piston, means for admitting fuel to and returning it from said cylinder, a fuel inlet and a fuelrelief valve positioned to control the inlet and return of fuel, and a single operating means for said valves, said means comprising a symmetrical cam, having two working faces inclined outwardly from the center of the cam toward each other, the upper ends of said faces being approximately in contact-with each other, a lever pivoted adjacent said earn, a pair of valve operating lever members positioned adjacent said cam, and linkage connecting each of said valve operating levers with said first mentioned lever, said valves and said valve operating levers being located on the same side of said cylinder.

2. In combination ina fuel pump for internal combustion engines, a pump, cylinder and piston, means for admitting fuel to and returning it from said cylinder, a fuel inlet and a fuel relief valve positioned to control the inlet and return of fuel, and a single operating means for said valves, said means comprising a symmetrical cam, having two working faces inclined outwardly from the center of the cam towards each other, the upper ends of said facesbeing approximately in contact with each other, a lever pivoted adjacent said cam, a pair of valve operating lever members positioned adjacent said cam, and linkage connecting each of said valve operating levers with said first mentioned lever, and means for simultaneously and in If in' co-ordination adjusting the fulcrums of said valve operating levers.

3. A fuel pump for internal combustion engines comprising a cylinder, a piston mounted within the cylinder for reciprocation, valve means for controlling the flow of fluid to and from said cylinder and including an inlet valve and a relief valve; means for maintaining said inlet valve and said relief valve normally closed, means for opening said inlet valve and said relief valve in timed relation comprising a pair of valve operating levers, eccentric fulcrum means for mounting each of said valve operating levers for rocking movement, a link member interconnecting said valve operating levers, cam means for concurrently rocking said valve operating levers and for reciprocating said piston, and means for driving said cam.

4. A fuel pump for internal combustion engines comprising a cylinder, a piston mounted within said cylinder for reciprocation, valve means for controlling the flow of fluid to and from said cylinder and including an inlet valve and a relief valve, means for maintaining said inlet valve and said relief valve normally closed, means for opening said inlet valve and said relief valve in timed relation comprisinga pairof valve operating levers, eccentric fulcrum means for mounting each of said valve operating levers for rocking movement, means for relatively adjusting said eccentric fulcrum means about their respective axes for varying the timed actuation of said inlet valve and said relief valve, a link member interconnecting said valve operating levers, and cam means for concurrently rocking said valve operating levers and for reciprocating said piston, and means for riving said cam.

5. A fuel pump for internal combustion engines comprising a pump cylinder, a piston mounted within said cylinder for reciprocation,'means for controlling the flow of fluid to and from said cylinder including an inlet valve and a relief valve, spring means for biasing said valves to closed position, means for opening said inlet and relief valves in timed relation comprising a pair of valve operating levers, eccentric fulcrum means for mounting said levers for rocking movement, cam means for actuating said piston, means for driving the cam, a pivoted lever having a free end terminating between said cam means and said piston, means operatively connecting the lever with said cam means and said piston, respectively, for actuating the piston when the cam is driven, and means for operatively connecting the valve r operating levers with said pivoted lever whereby said inlet and relief valves are concurrently actuated in timed relation.

6. A fuel pump for internal combustion engines comprising a pump cylinder, a piston mounted within said cylinder for reciprocation, means for controlling the flow of fluid into and from said cylinder including an inlet valve and a relief valve, spring means for biasing said valves to closed position, means for opening said inlet and relief valves in timed relation comprising a pair of valve operating levers, eccentric fulcrum means for mounting-said levers for rocking movement, cam means for actuating said piston, means for driving the cam, a pivoted lever having a free end terminating between said cam means and said piston, means operatively connecting the lever with said cam means and said piston, respectively, for actuating the piston when the cam is driven, means for operatively connecting the valve operating levers with said pivoted lever whereby said inlet and relief valves are concurrently actuated in timed relation, and means for relatively adjusting said eccentric means about their respective axes for varying the timed actuation of said valves.

7. A fuel pump for internal combustion engines comprising a pump cylinder, a piston mounted Within the cylinder for reciprocation, means for controlling the flow of fluid to and from said cylinder comprising an inlet valve and a relief valve, spring means for biasing said valves to closed position, means for opening said valves in timed relation including a pair of push rods mounted for reciprocation on opposite sides of the pump cylinder and disposed in generally parallel relation to said piston, a pair of valve operating levers, eccentric means for mounting said levers for rocking movement, abutment means carried by each of said valve operating levers in operative engagement, respectively, with said push rods, a pivoted lever having a free end disposed in substantial alignment with the pump piston, cam means, means operatively connecting said pivoted lever with the cam means and said piston, means for driving the cam to cause reciprocation of the piston, link means operatively connecting the valve operating levers with each other and with said pivoted lever for concurrently rocking the levers in timed relation, and means for relatively adjusting said eccentric fulcrum means for varying the timedactuation of said valve members.

8. A fuel pump for internal combustion engines comprising a pump cylinder, a piston mounted within the cylinder for reciprocation, means for controlling the flow of fluid to and from said cylinder comprising an inlet valve and a relief valve, spring means for biasing said valves to closed position, means for opening said valves in timed relation including a pair of push rods mounted for reciprocation on opposite sides of the pump cylinder and disposed in generally parallel relation to said piston, a pair of valve operating levers, eccentric means for mounting said levers for rocking movement, abutment means carried by each of said valve operating levers in operative engagement, respectively, with said push rods, a pivoted lever having a free end disposed in substantial alignment with the pump piston, cam means, means operatively connecting said pivoted lever with the cam means and said piston, means for driving the cam to cause reciprocation of the piston, link means operatively connecting the valve operating levers with each other and with said pivoted lever for concurrently rocking the levers in timed relation, means for relatively adjusting said eccentric fulcrum means for varying the timed actuation of said valve members, said abutment means being disposed on opposite sides of the respective axes of the fulcrum means, and said eccentric adjustment means including means interconnecting said fulcrum means for rotation in opposite directions about their respective axes.

HEINRICH WALTI. 

